Preemptive Handover Preparation and Tracking/Paging Area Handling and Intelligent Route Selection in a Cellular Network

ABSTRACT

A concept for handovers in cellular networks, a concept for improved handling of tracking/paging areas for, for instance, user entities in inactive modes and a concept for enabling intelligent route selection in cellular networks are presented.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending U.S. patent applicationSer. No. 16/431,647 filed Jun. 4, 2019, which is a continuation ofInternational Application No. PCT/EP2018/000109, filed Mar. 22, 2018,which is incorporated herein by reference in its entirety, andadditionally claims priority from European Application No. 17162641.9,filed Mar. 23, 2017, which is also incorporated herein by reference inits entirety.

BACKGROUND OF THE INVENTION

The present application is concerned with a concept for handovers incellular networks, a concept for improved handling oftracking/paging/RAN notification areas for, for instance, user entitiesin inactive modes and a concept for enabling intelligent route selectionin cellular networks.

Handovers of connections such as an ongoing call or a data session, or auser entity from one cell to another is an oft-occurring process and thecontrol signaling used to establish such handovers consumes aconsiderable amount of the available radio and network resources andcurrently has an undesirable high latency for high reliabilitycommunications. Any reduction in the control signaling overhead and/orlatency would be desirable.

Handovers take place in an activated mode of a user entity. Most of thetime, however, user entities are not in an active mode or, differentlyspeaking, most of the time there is no need for a continuous datacommunication for a user entity, but rather, discontinuously orintermittently, packets of a certain data session, are to be transmittedto/from the user entity. In such a case, continuously performinghandovers might be unnecessary as long as a user entity is within acertain tracking/paging area. Merely when leaving the tracking/pagingarea, the user entity informs the cellular network on its new locationor position. This entails, however, power consumption by the user entityand accordingly, it would be desirable to have a concept at hand whichallows for reduction in this power consumption.

SUMMARY

An embodiment may have a cellular network supporting a preemptivepreparation of a handover for a user entity.

Another embodiment may have a cellular network apparatus, configured toanalyze a predetermined set of cells around a position of user entitywith respect to a set of possible routes leading away from the userentity's position to determine a favorite route among the set ofpossible routes in terms of connectivity of the user entity; and providefor the user entity information about the favorite route.

Another embodiment may have a user entity for communication over acellular network, wherein the user entity is configured to gaininformation on a predicted future route of the user entity and informthe cellular network on the predicted future route.

Another embodiment may have a user entity for communication over acellular network, wherein the user entity is configured to manage a setof one or more preemptively prepared handovers.

Another embodiment may have a base station of a cellular networkconfigured to determine a preliminary set of one or more target basestations of the cellular network based on a predicted future route of auser entity currently connected to the cellular network via the basestation or triggered by the user entity entering a predetermined area,query each of the preliminary set of one or more target base stationsregarding an accessibility of the cellular network via the respectivetarget base station, receive, from each of the preliminary set of one ormore base stations, an answer to the query, sending to the user entity aschedule indicating, for each of a set of one or more base stationswithin the preliminary set, a temporal access interval and one or moreaccess parameters indicating that the user entity may access thecellular network via the respective base station during the temporalaccess interval using the one or more access parameters, cutting, uponreceipt of an access confirmation from any of the set of one or morebase stations, a connection to the user entity.

Another embodiment may have a cellular network configured to establishfor a predetermined user entity a schedule of a time-varyingtracking/paging area spanned by a time-varying set of one or more basestations, or to establish the time-varying tracking/paging area andprovide the user entity with updates on changes of the time-varyingtracking/paging area.

Another embodiment may have a cellular network configured to determinefor a predetermined user entity a tracking/paging area depending on apredicted future route of a user entity.

Still another embodiment may have a user entity for communicating over acellular network, wherein the user entity is configured to continuouslycheck a schedule of a time-varying tracking/paging area whether the userentity leaves the time-varying tracking area and send a tracking/pagingarea update message to the cellular network in case of the user entityleaving the time-varying tracking/paging area.

Another embodiment may have a method for operating a cellular networkhaving preemptively preparing a handover for a user entity.

According to another embodiment, a method for operating a cellularnetwork may have the steps of: analyzing a predetermined set of cellsaround a position of user entity with respect to a set of possibleroutes leading away from the user entity's position to determine afavorite route among the set of possible routes in terms of connectivityof the user entity; and providing information about the favorite routefor the user entity.

According to another embodiment, a method for communication over acellular network may have the steps of: gaining information on apredicted future route of the user entity and informing the cellularnetwork on the predicted future route.

Another embodiment may have a method for communication over a cellularnetwork, having managing a set of one or more preemptively preparedhandovers.

According to still another embodiment, a method of operating a basestation of a cellular network may have the steps of: determining apreliminary set of one or more target base stations of the cellularnetwork based on a predicted future route of a user entity currentlyconnected to the cellular network via the base station or triggered bythe user entity entering a predetermined area, querying each of thepreliminary set of one or more target base stations regarding anaccessibility of the cellular network via the respective target basestation, receiving, from each of the preliminary set of one or more basestations, an answer to the query, sending to the user entity a scheduleindicating, for each of a set of one or more base stations within thepreliminary set, a temporal access interval and one or more accessparameters indicating that the user entity may access the cellularnetwork via the respective base station during the temporal accessinterval using the one or more access parameters, and cutting, uponreceipt of an access confirmation from any of the set of one or morebase stations, a connection to the user entity.

According to another embodiment, a method for operating a cellularnetwork may have the step of: establishing for a predetermined userentity a schedule of a time-varying tracking/paging area spanned by atime-varying set of one or more base stations, or establishing thetime-varying tracking/paging area and providing the user entity withupdates on changes of the time-varying tracking/paging area.

According to another embodiment, a method for operating a cellularnetwork may have the step of determining for a predetermined user entitya tracking/paging area depending on a predicted future route of a userentity.

According to another embodiment, a method for communicating over acellular network may have the steps of: continuously check a schedule ofa time-varying tracking/paging area whether the user entity leaves thetime-varying tracking area and send a tracking/paging area updatemessage to the cellular network in case of the user entity leaving thetime-varying tracking/paging area.

Another embodiment may have a non-transitory digital storage mediumhaving stored thereon a computer program for performing a method foroperating a cellular network having preemptively preparing a handoverfor a user entity, when said computer program is run by a computer.

The present application provides, in accordance with a first aspect ofthe present application, a concept for improved handovers in a cellularnetwork. This object is achieved by the subject matter of theindependent claims of the present application in accordance with thefirst aspect of the present application.

In accordance with a second aspect of the present application, thepresent application provides a concept for an improved handling of userentities which are not in an active state.

One idea underlying some of the embodiments of the present applicationin accordance with the first and second aspects aims at achieving theabove-identified improvements, by using a prediction of a future routeof a user entity to improve the handover handling and/or the handling ofnon-active user entities, respectively. In particular, being able toexploit a predictive future route of the user entity allows forpreemptive preparation of one or more handovers on the side of thecellular network. This, in turn, alleviates the control data overheadand/or reduces latency incurred by handovers. Such predictive futureroutes may also be advantageously used, for instance, in setting-up atime-varying tracking/paging area within which the user entity isallowed to stay without any need for keeping the cellular networkupdated on the exact cell within the tracking/paging area within whichthe user entity currently resides. This, in turn, may reduce the powerconsumption occurring in the user entity for indicating to the cellularnetwork any departure from the tracking/paging area as thetracking/paging area may be adapted better to the route actually takenby the user entity.

A further idea which underlies some of the embodiments of the presentapplication in accordance with the first aspect is the fact that apreemptive preparation of a handover enables the reduction in the amountof control signaling for handovers wherein, depending on thesesituations where such preemptive preparation of handovers is performed,the possible wastage of network resources which might be incurred by thepreemptive preparation of the handovers in order to, for example, meet acertain promise that the user entity may access the cellular network ata predetermined temporal access interval using one or more accessparameters at a certain base station of the cellular network, may bekept comparatively low. In particular, a preemptive preparation ofhandovers avoids, for a short-term or mid-term future, control signalingfor handovers which will very likely occur with respect to a certainuser entity. This, in turn, reduces control signaling at base stationsfor which the preemptive preparation of the handover has been performed,and reduces or avoids otherwise possibly occurring latency due to, forinstance, the performance of handover related protocol signaling whichthen has to take place anytime just before the user entity seeks to moveto the next cell. Naturally, this idea may be combined with the firstidea so as to improve the selection of the set of base stations withrespect to which the preemptive preparation of handovers is performed.Additionally or alternatively, the fact that the user entity enters apredetermined area may be identified as a circumstance where apreemptive preparation of a handover is favorably performed. Forinstance, such a predetermined area may be associated with a very highlikelihood that the user entity will, in a near future, enter the cellof a predetermined other, i.e. target, base station and accordingly,performing a preemptive preparation of a handover towards this basestation, may favorably reduce otherwise-occurring handover latencyand/or control signaling associated with the handover.

Even additionally or alternatively, a further idea underlying someembodiments of the present application in accordance with the first andsecond aspects is the fact that some sort of scheduling of atracking/paging area and/or handovers with respect to time, mayalleviate the control signaling otherwise occurring if the schedulingwould be replaced by a passive triggering of otherwise usedtracking/paging area updates and handovers, namely, merely when needed.This idea may, obviously also be combined with the idea of exploiting aprediction of a future route of the user entity.

In accordance with a further aspect of the present application, thepresent application provides an improved concept for serving a userentity via a cellular network; namely, in a manner increasing theconnectivity of the user entity. This object is achieved by the subjectmatter of the independent claim of the third aspect.

In particular, an idea on which embodiments of the third aspects arebased, is that an analysis of a predetermined set of cells around aposition of a user entity with respect to a set of possible routesleading away from the user entity's position to determine a—in terms ofsome predetermined criterion or criteria—favorite route among the set ofpossible routes in terms of connectivity of the user entity andproviding for the user entity information about the favorite route, maybe used to provide users of such a user entity with the opportunity totake this favorite route into account in planning their further journey;namely, in a manner taking into account the connectivity of the userentity and the time to come. The thus selected route could, forinstance, be called a best connected/served route.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present application are described below with respectto the Figures, in which:

FIG. 1 shows a schematic block diagram illustrating a cellular networkand a UE within the cellular network in order to illustrate a handover(HO);

FIG. 2 shows a temporal order of steps performed in a handover process;namely, an X2-based HO procedure according to [1] [6] wherein thediagram of FIG. 3 distinguishes, by arranging the different entitiesparticipating in the HO procedure, side by side between the side orentity at which a certain step is performed or from whom to whom acertain signal is sent at a certain step, with a number of stepsillustrated in FIG. 2 being 12;

FIG. 3 shows a temporal order of steps in a manner similar to FIG. 2 buthere an S1 based HO procedure according to [1];

FIG. 4 shows a schematic block diagram illustrating a cellular networkand a UE communicating with the same, wherein FIG. 4 also shows the UEas being currently connected to the cellular network via a source basestation and as moving to other base stations of the cellular networkwhich, thus, form target base stations with respect to which an handoveris to be performed, wherein the cellular network, the UE and the basestations shown in FIG. 4 may be embodied according to the presentapplication;

FIG. 5 shows a schematic diagram illustrating the preemptive preparationof handovers realized by the entities presented in FIG. 4 in accordancewith an embodiment;

FIG. 6 shows a schematic block diagram illustrating a cellular network,a UE and signaling used in order to realize a preemptive handoverpreparation in an LTE framework;

FIG. 7 shows a table illustrating a possible signaling of preemptivelyprepared handovers in accordance with an embodiment;

FIG. 8 shows a sequence of steps involved in a preemptively preparedhandover in a manner similar to the illustration used in FIGS. 2 and 3,in accordance with an embodiment of the present application;

FIG. 9 shows a schematic block diagram of a predictive handover (P-HO)architecture and message flow overview in accordance with an embodiment;

FIG. 10 shows a schematic block diagram illustrating an example for anout-of-coverage HO process;

FIG. 11 shows a schematic diagram illustrating the state machine ofconnection modes discussed in RAN2 for reduced signaling traffic whereinreference is made to R2-168345 [3];

FIG. 12 shows a schematic diagram illustrating clusters of base stationcells to tracking areas separated by tracking/paging area borders knownfrom, for instance, [11]; in other words, non-access stratum (NAS) asdepicted in FIG. 12;

FIG. 13 shows a block diagram of a RN architecture according to [7];

FIG. 14 shows a block diagram of a V2X broadcast architecture accordingto [8] as an example where embodiments of the present application mightadvantageously be used;

FIG. 15 shows a block diagram of a V2X eNB type roadside unit developedat the edge as an example of how a prediction of an HO process may bemade faster;

FIG. 16 shows a schematic diagram illustrating a data split at thebearer level according to [11];

FIG. 17 shows a schematic diagram illustrating a data split at thepacket level according to [11];

FIG. 18a-b shows a sequence of steps involved in a DC sequence chartaccording to [12], the sequence of steps being illustrated in a mannersimilar to the manner the sequence of step is illustrated in FIGS. 2 and3;

FIG. 19 shows a schematic block diagram of a cellular network, a UE andthe involved base stations in accordance with embodiments of the presentapplication where non-active UEs are efficiently handled usingintelligent definition of the tracking/paging area;

FIG. 20 shows a schematic diagram illustrating the mode of operation ofthe entities involved in the scenery of FIG. 19 in accordance with anembodiment where a time-varying tracking/paging area is used; and

FIG. 21 shows a schematic diagram illustrating the mode of operation ofthe entities involved in the scenery shown in FIG. 19 in accordance withan embodiment where the tracking/paging area is defined depending on apredicted future route of the UE.

DETAILED DESCRIPTION OF THE INVENTION

In the following, various embodiments of the present application aredescribed. These embodiments relate to different aspects of the presentapplication, namely the aspect of efficiently handling handovers, theconcept of efficiently controlling tracking/paging areas within whichuser entities may efficiently reside in a non-active mode, and theconcept of providing users of user entities with the opportunity to takethe aim of a good connectivity into account in selecting the route to betaken in the time to come.

The description of these embodiments starts with an introduction and atechnical overview with respect to the first concept relating tohandovers. In general, a base station can be referred to as eNB (namingin the LTE context) or gNB (naming in the NR/5G context). In thefollowing, it is not distinguished between these three terms. A userterminal/mobile user can be referred to as user equipment or user entity(UE).

There can be loss of connectivity during handovers in New Radio (NR) for5G, especially for cases involving vehicular traffic, e.g. cars, busses,trucks, autonomous driving, drones and unmanned aerial vehicles (UAVs),planes, etc. The problem is threefold:

-   -   1. The number of vehicles is increasing, causing increased        signaling demand for handover processes (HOs),    -   2. The new mobility services, e.g. assisted driving etc.,        introduce new service requirements in terms of traffic models,        e.g. reliability constraints like packet error rates (PER),        throughput demands and packet sizes (e.g. high numbers of small        control packets) as well as more stringent latency constraints,    -   3. State-of-the-Art handover (HO) is not optimized fully, since        information wrt. localization (indoor and outdoor) as well as of        traffic routes has vastly improved over the past years and        enables track prediction of UEs connected to the cellular        infrastructure. This is more the case for autonomous UEs with        cloud connectivity, which have a tight communication link via        wireless.        Significant HO overheads are caused when vehicles are rapidly        moving across different cells during a given period. It would be        favorable to improve the mobility services for        vehicular/airborne UEs, which are in connected/active or lightly        connected/inactive mode, especially in scenarios with        vehicle-to-infrastructure (V2X), vehicle-to-vehicle (V2V) and        Unmanned Aerial Vehicle (UAV) scenarios.

These services shall be enhanced in order to improve performance andenhance reliability of the handover (HO) procedure through signalingprocedures that specifically introduce prediction and improve thereliability of UE context transfer to the target eNBs during thepredictive HO procedure.

The current HO procedures in LTE are designed to cater for scenarioswhere a UE transitions from a source eNB 12 to the target eNB 14 asindicated in FIG. 1 or from a cell 16 of eNB 12 to a cell 18 of eNB 14.The focus of this invention is on Intra-RAT HO procedures whileInter-RAT mobility is not precluded.

There are two types of HO procedure in LTE for UEs in active mode:

-   -   1. the X2-handover procedure,    -   2. the S1-handover procedure.        1. X2-based HO: The X2-handover procedure is illustrated in FIG.        2 and is normally used for the intra-eNB handover. The handover        is directly performed between two eNBs via an X2 interface 20        connecting both eNBs 12 and 14, which makes the preparation        phase quick. The MME as part of a core network 24 of the        cellular network 24 which also comprises the eNB 12 and 14 is        only informed at the end of the HO procedure 26, once the HO is        successful in order to trigger the path switch. Release of        resources at the source side is directly triggered from the        target eNB. The X2-handover procedure 26 consists of 3 basic        phases:    -   1) Preparation phase 26 a (steps 4-6),    -   2) Execution phase 26 b (steps 7-9),    -   3) Completion phase 26 c (after step 9).        An overview of X2-based handover procedures based on FIG. 2 [6]        is outlined below:

-   1. The Source eNB 12 contains the UE context which consists of    information related to area roaming and access restrictions and was    initially provided during the connection establishment or Tracking    Area (TA) update.

-   2. The UE measurement procedures can be configured via the SeNB and    assist with the UE's connection mobility.

-   3. The Source eNB receives a measurement report from the UE as well    as Radio Resource Management (RRM) Information to enable whether a    HO decision is performed.

-   4. The source eNB issues a HO REQUEST message to the target eNB    passing information entailed to prepare the HO at the target side.    This information may include UE X2 signaling context reference at    source eNB, UE S1 EPC (Evolved Packet Core) signaling context    reference, target cell ID, K_(eNB*), RRC (Radio Resource Control)    context including the C-RNTI (Cell-Radio Network Temporary    Identifier) of the UE in the source eNB, AS (Access    Stratum)-configuration, E-RAB (E-UTRAN Radio Access Bearer) context    and physical layer ID of the source cell+short MAC-I (Message    Authentication Code) for possible RLF (Radio Link Failure) recovery.    UE X2/UE s1 signaling references enable the target eNB to address    the source eNB and the EPC. The E-RAB context includes RNL (Radio    Network Layer) and TNL (Transport Network Layer) addressing    information, and QoS (Quality of Service) profiles of the E-RABs.

-   5. Resource setup primarily configures resources to query if the    resources can be granted by the target eNB and also performs    admission control on the received E-RAB QoS information to increase    likelihood of a successful HO. “The target eNB configures the used    resources according to the received E-RAB QoS information and    reserves a C-RNTI and optionally a RACH preamble. The    AS-configuration to be used in the target cell can either be    specified independently (i.e. an “establishment”) or as a delta    compared to the AS-configuration used in the source cell (i.e. a    “reconfiguration”)”.

-   6. “The target eNB prepares HO with L1/L2 and sends the HANDOVER    REQUEST ACKNOWLEDGE to the source eNB. The HANDOVER REQUEST    ACKNOWLEDGE message includes a transparent container to be sent to    the UE as an RRC message to perform the handover. The container    includes a new C-RNTI, target eNB security algorithm identifiers for    the selected security algorithms, may include a dedicated RACH    preamble, and possibly some other parameters i.e. access parameters,    SIBs, etc. The HANDOVER REQUEST ACKNOWLEDGE message may also include    RNL/TNL information for the forwarding tunnels, if applicable. NOTE:    As soon as the source eNB receives the HANDOVER REQUEST ACKNOWLEDGE,    or as soon as the transmission of the handover command is initiated    in the downlink, data forwarding may be initiated.”

-   7. “The target eNB generates the RRC message to perform the    handover, i.e. RRCConnectionReconfiguration message including the    mobilityControlInformation, to be sent by the source eNB towards the    UE. The source eNB performs the integrity protection and ciphering    of the message. The UE receives the RRCConnectionReconfiguration    message with parameters used (i.e. new C-RNTI, target eNB security    algorithm identifiers, and optionally dedicated RACH preamble,    target eNB SIBs, etc.) and is commanded by the source eNB to perform    the HO. The UE does not need to delay the handover execution for    delivering the HARQ/ARQ responses to source eNB.”

-   8. “The source eNB sends the SN (Sequence Number) STATUS TRANSFER    message to the target eNB to convey the uplink PDCP (Packet Data    Convergence Protocol) SN receiver status and the downlink PDCP SN    transmitter status of E-RABs for which PDCP status preservation    applies (i.e. for RLC AM (Acknowledge Mode)). The uplink PDCP SN    receiver status includes at least the PDCP SN of the first missing    UL SDU and may include a bit map of the receive status of the out of    sequence UL SDUs that the UE needs to retransmit in the target cell,    if there are any such SDUs. The downlink PDCP SN transmitter status    indicates the next PDCP SN that the target eNB shall assign to new    SDUs, not having a PDCP SN yet. The source eNB may omit sending this    message if none of the E-RABs of the UE shall be treated with PDCP    status preservation.”

-   9. When the UE has successfully accessed the target cell, the UE    sends the RRCConnectionReconfigurationComplete message (C-RNTI) to    confirm the handover, along with an uplink Buffer Status Report,    whenever possible, to the target eNB to indicate that the handover    procedure is completed for the UE. The target eNB verifies the    C-RNTI sent in the RRCConnectionReconfigurationComplete message. The    target eNB can now begin sending data to the UE.

-   10. “The target eNB sends a PATH SWITCH REQUEST message to MME to    inform that the UE has changed cell.”

-   11. “The MME confirms the PATH SWITCH REQUEST message with the PATH    SWITCH REQUEST ACKNOWLEDGE message.”

-   12. “By sending the UE CONTEXT RELEASE message, the target eNB    informs success of HO to source eNB and triggers the release of    resources by the source eNB. The target eNB sends this message after    the PATH SWITCH REQUEST ACKNOWLEDGE message is received from the    MME.”    However, when there is no X2 interface 20 between the eNBs (e.g.    legacy eNBs 12 and 14 based on UTRAN architecture), or if the eNB 12    has been configured to initiate the handover towards a particular    target eNB via the S1 interface 28 which connects the eNBs with the    core network 22, then the S1 handover procedure illustrated in FIG.    3 will be triggered. The S1-handover procedure consists of 3 basic    phases:

1) Preparation phase 30 a involving the core network, e.g. EPC, wherethe resources are first prepared at the target side (steps 2-8),

2) Execution phase 30 b (steps 8-12),

3) Completion phase 30 c (after step 13).

As an overview of S1-based HO Handover Procedures reference is made to[6]. For a detailed description also refer to the steps of the previousX2-based HO procedure.

As to Steps 13-15, it is noted that some are special to the S1-based HO30, and comprise of acknowledgement and update information to the targetMME.

Next, UE context transfer in 4G/5G is referred to.

The radio resource control (RRC) context transfer is an importantprocedure of the HO process. The MME 32 as a part of the core network 22creates a UE context when a UE 12 is switched on and subsequentlyattempts to connect to the network 24. A unique short temporary identityis assigned, also known as the SAE Temporary Mobile Subscriber Identity(S-TMSI), to the UE 12 that identifies the UE context in the MME 32.This UE context contains user subscription data originally obtained froma Home Subscriber Server 34 (HSS) also being part of the core network22. The local storage of subscription data in the MME 32 enables fasterexecution of procedures such as bearer establishment since it removesthe need to consult the HSS every time. In addition, the UE context alsoholds dynamic information such as the list of bearers that areestablished and the terminal capabilities [2]. During the P-HO process,the eNB 12 would be used to forward the UE's radio resource control(RRC) context to subsequent target eNBs such as eNB 14.

After having described, rather generally, the task of handovers incellular networks and how these handovers were treated so far in LTE, inthe following, the description of the present application provides apresentation of embodiments relating to this task which achieve animprovement over these handover mechanisms used in LTE so far in termsof control signaling overhead on the one hand and/or handover-relatedlatency on the other hand.

Later on, the description proceeds with a description as to how some ofthe embodiments might be embedded into, or implemented to addressvarious specifics associated with, nowadays mobile networks.

FIG. 4 shows in a manner reusing the reference numbers of FIG. 1 forentities fulfilling the same task in the overall system shown in FIG. 4,a cellular network 24 comprising a plurality of base stations 11spatially spread so that their cells 15, within which each base station11 serves user entities residing in the respective cell 15 so as toconnect them to the cellular network 24 by wireless communication, covera certain region or area such as a geographical region 40 in a manner sothat cells 15 abut or overlap each other. The cells 15 are quasi-definedby the respective wireless communication reach of each base station 11.The cellular network of FIG. 4 also comprises a core network via which,and to which, each base station 11 is connected via a respectiveinterface 28 such as some cable based network such as electrical oroptical cables. As already described with respect to FIG. 1, the basestations 11 might be connected to each other directly, too, such as viainterface 20 shown in FIG. 1 which might be cable-based or wireless suchas an optical connection.

FIG. 4 also shows a user entity or user equipment 10. It is currentlyserved by base station 12. That is, base station 12 is a special basestation 11 with respect to UE 10, namely the source base station 12.That is, UE 10 is located within cell 15 of base station 12 and basestation 12 communicates with the UE 10 via radio resources it assigns toUE 10. The share of radio resources assigned to UE 10 depends on manyfactors such as subscriber data of UE 10, number of further UEscurrently served by base station 10 and so forth. It is assumed that UE10 is currently in a connected or active mode. That is, UE 10 has, forinstance, one or more current communication sessions running such as acall and/or data session. That is, the UE 10 which might be a mobilephone, a laptop or some other mobile or non-mobile device, may have oneor more applications such as computer programs or the like, runningthereon which communicate via base station 12 over network 34 with somethird party which might be an entity within the cellular network 24, butmay alternatively be a third party device being external to the cellularnetwork 24 and connected to core network 34 via the Internet or someother external network 42. The core network 34 or some entity withincore network 34 such as MME 32 contains or manages a context for each UE10 currently served within region 40. For instance, such context orcontext data could indicate which sessions are currently active withrespect to each UE, at which base station 11 the respective UE isserved, i.e., via which base station 11 the respective UE is connectedto the cellular network 24, and/or further information such assubscriber data or the like. In order to associate such contexts withthe associated UEs, core network 34 assigns identifiers to the UEs. Thecurrently serving base station 12 also knows about, or stores, thecontext of UE 10 and knows about the ID used within core network 34 withrespect to UE 10. Based on the context data, core network 34 is able toforward packets of any communication session associated with UE 10towards base station 12, which, in turn, forwards the same wirelessly toUE 10.

The cellular network 24 of FIG. 4 is configured to support a preemptivepreparation of a handover for user entity 10. This means the following.It might be, that cellular network 24, optionally, has theafore-mentioned functionality of initiating a handover of UE 10 toanother, i.e., a target base station; namely, one of the neighboringbase stations neighboring base station 12, on the basis of an evaluationof measurements made by the UE 10 which measure the connection qualitybetween UE 10 and base station 12 as well as between UE 10 and any ofthe neighboring base stations 11, provided the UE 10 is within the reachof the respective neighboring base station 11. Such passive activationwould mean that the cellular network 24 comes to the conclusion that ahandover to such a neighboring target base station would be advantageousaccording to some criteria such as connection quality and/or othercriteria. The cellular network 24 of FIG. 4, however, supports aspeculative or preemptive preparation of a handover for a user entitysuch as user entity 10. When preemptively preparing a handover for userentity 10, the cellular network 24 establishes, for each of a set of oneor more target base stations 14 a and 14 b of the cellular network 24, atemporal access interval and one or more access parameters so that theuser entity 10 may access the cellular network 24 via the respectivebase station 14 a, 14 b during the temporal access interval using theone or more access parameters established for the respective basestation. This means, that for such a set of base stations 14 a, 14 b,the handover is, as far as the cellular network's side is concerned,already done. It is merely up to the UE 10 or up to other circumstancesdiscussed further below, whether the access opportunity provided withinthe temporal access intervals using the one or more access parametersfor base stations 14 a, 14 b is actually used by UE 10. The target basestations 14 a, 14 b to which a handover has been preemptively prepared,reserve a certain access channel or radio access channel using the oneor more access parameters established for the respective base stationduring the temporal access interval.

To have a better understanding of this, reference is made to FIG. 5.FIG. 5 shows the process of preemptive preparation of the handover byway of establishing respective temporal access interval and one or moreaccess parameters for one or more target base stations by illustratingthe temporal sequence of steps performed along a temporal access t. Asshown in FIG. 5, the preemptive preparation of a handover is triggeredat a time instant t₀. In other words, at this time instant t₀, thecellular network determines a preliminary set 50 of one or more basestations of the cellular network with respect to which a preemptivepreparation of a handover might be performed. This preliminary set 50 ofbase stations is determined by the cellular networks so that their cells15 cover an area where the UE 10 will probably move in the next futureupon leaving the cell of current source base station 12. As describedlater on, for instance, cellular network 24 may determine thepreliminary set 50 depending on information on a predicted future routeof the user entity. In FIG. 4 such a predicted future route isillustrated using a dashed line 52. The same crosses the cells of basestation 14 _(a) and 14 _(b). FIG. 5 illustrates the preliminary set 50to be composed of, generally, base stations 14 ₁ . . . 14 _(M) with M≥N.The temporal length of the predicted future route 52 may cover a certaintemporal interval 54 starting from time instant t₀ and lasting, forinstance, for more than 10 seconds, 1 minute or even 5 minutes. Thetemporal length 54 might be determined variably as well and might beadapted, for instance, to the prediction accuracy of the predictedfuture route 52. The cellular network might receive the information onthe predicted future route 52 of the user entity 10 from the user entity10 itself such as, for instance, from an application running on the userentity or a certain component thereof being able to determine theposition of the user entity 10 such as a navigation system or the like,or from some other module of the UE. The information transmission maytake place during RRC Connection establishment, for instance.Alternatively, information on the predicted future route 52 of the userentity 10 might come from a device other than the cellular network 24and the user entity 10. Such other device could be, for instance, asystem which tracks the user entity 10, but resides external to cellularnetwork 24. The information could be provided, for instance, by anexternal entity such as a V2V/V2X server, or from an over-the-top (OTT)entity such as Google 6. It might even be that the other device isresponsible for granting allowance for the future route 2 such as atraffic management system which could be, for instance, responsible, forflight routes of drones as examples for UEs or the like. Additionally oralternatively, the cellular network 24 may determine the predictedfuture route 52 of the user entity itself such as by triangulationapplied onto signals sent by the UE 10 and received by several of thebase stations 11 or the like, or by extrapolating path 52 from a pasttravel path of UE 10 defined by updates on the UE's current positionwhich the network 24 receives from the UE 10. The derivation of thepredicted future route 52 may involve, in any case, irrespective of theentity performing the derivation, a type of extrapolation or predictionon the basis of additional information in addition to a current positionof the user entity 10 such as a route taken by the UE 10 immediately upto time instant t₀, map data indicating a map of region 40 such as astreet map or the like, and/or user preference data associated with theUE 10 having been gathered based on an evaluation of routes taken by theUE 10 in the past. Preliminary set 50 would then be determined so thatthe base station's cells within the set 50 would be crossed by route 52.The UE 10 is, thus, likely to need a handover at at least a subset ofbase stations of set 50. It should be noted, however, that set 50 may,alternatively, be determined by the cellular network 24 by means otherthan based on an evaluation of predicted future route 52. The predictedroute 52 could, for instance, be determined by a V2X broadcast server,or using information from other mobile users, e.g. by sensor fusion of aset of predicted routes from multiple UEs. Further, base station 12could be configured to request the route vector 52 as a kind ofmeasurement report, including route updates and top-m routes e.g. route1, route 2, route 3, . . . .

The use of route 52 for determining set 50 is not necessary. Forinstance, the mere fact or circumstance that UE 10 enters a certainpredetermined area 56 may be an indicator that there is a highprobability that the user entity 10 will be, during a certain timeinterval 54 following time instant t₀ at which the UE 10 entered area56, in a certain area, or will travel along a certain path or route sothat set 50 could be automatically determined albeit fixedly associatedwith, the event of UE 10 entering area 56 at time instant t₀. Forinstance, the area 56 could be one end of a street without any crossinguntil reaching, via a certain path 52, namely the street, a firstcrossing and accordingly, as soon as the UE 10 enters the street at thispoint, it is very likely that the UE 10 will follow this route/street52. Similarly, imagine a UE 10 enters a tunnel at a first end and thetunnel being long so as to lead to another cell. While it might beunknown which street the UE takes after the tunnel, it is very likelythat the UE will continue its journey after the tunnel and accordingly,set 50 could be determined so as to cover base stations surrounding thatside of the tunnel.

Even alternatively, the prediction that there is a high probability thatthe user entity 10 will be, during some time interval 54 following atime instant t₀, in a certain area, or will travel along a certain pathor route, could be triggered on the basis of an evaluation of a historyof a route of the CE in the past such as a time interval preceding, oreven immediately preceding, time instant t₀. In addition to the userentity 10 entering area 56, for instance, a current heading direction ofUE 10 could be taken into account so as to trigger a preemptive HOpreparation merely in case of the heading direction pointing into acertain direction or field of directions in addition to UE entering 56.For instance, preemptive preparation of HO could be triggered by theuser entity coming from predetermined area 56. Generally speaking, ahistory of UE positions could be evaluated in order to see whether thishistory meets some criteria and if so, preemptive HO could be initiated.The history of positions may be logged in any granularity or accuracy.For instance, a previous set of serving base stations or a list ofprevious base stations along the route of the user entity, i.e. somemobility history, could be used to this end. Irrespective of area drivenor history-of-positions driven, the triggering could be done based onmatching current UE's position, current UE's heading direction and/ormost recent history of UE positions against one or more predeterminedcriteria which are independent from the most recent connection qualitymeasured by the UE with respect to its communication connection to thesource base station 12 and/or any surrounding base station 11.

That is, along with determining the preliminary set 50 of base stations,cellular network 24 determines for each base station within set 50 anexpected time t₁ . . . t_(M) at which the user entity enters therespective base station's cell 15, i.e., is within its reach.Accordingly, base station 12, i.e., the source eNB, queries each of thepreliminary set 50 of target base stations regarding an accessibility ofthe cellular network 24 via the respective target base station at therespective expected time t_(i). As an outcome of this query, basestation 12 of cellular network 24 receives from each of the preliminaryset 50 of base stations, an answer to the query. While there may benone, one, or more than one base station within preliminary set 50 whichdenies the accessibility, there may be a set of base stations, let's sayN base stations with N≥1 and N≤M which answer the query by way ofindicating a temporal access interval 60 at which the respective basestation is accessible by user entity 10 provided that user entity 10uses the one or more access parameters indicated by the respective basestation in the answer to the query. For instance, FIG. 5 illustratesthat a certain access interval 60 overlaps a first expected time t₁. Abase station of set 50 within the cell of which the user entity 10 isexpected to be as time instant t₁, thus, allows user entity 10 to accessthe cellular network 24 using one or more access parameters viacorrespondingly reserving respective access radio resources during timeinterval 60. The same might apply for the other expected times when theassociated target base stations may all be different for the expectedtimes, but this is not necessarily the case. After the query and theanswers thereto, base station 12 is, thus, able to send to the userentity 10 a schedule 62 which indicates, for each of the set 64 of oneor more base stations for which a temporal access interval 60 and one ormore access parameters 66 have been determined, the temporal accesstemporal interval 60 as well as the one or more access parameters. Thisschedule 62 indicates to the user entity 10 that the same may access thecellular network 24 via the respective base station 14 _(x) during thetemporal access interval indicated, for instance, by its beginning orstart at t^(x) _(start) using the associated one or more accessparameters p^(x) _(access) with x being element of {a, b . . . }, i.e.being an index into set 64. In other words, schedule 62 could besubmitted as an ordered list of elements, the elements having a temporaldependency, or the schedule 62 could be submitted as a set of elements.An even alternatively, schedule 62 could be submitted as a list of listsor sets which may be ranked, e.g. top-m. Each such element would then beassociated with a certain target base station, define its accessinterval 60 and the one or more access parameters 66. Thereinafter, i.e.of submission of schedule 62 to UE 10, the preemptive preparation or oneor more handovers is finished and the user entity has been notifiedthereabout and it is, from the sending of the schedule 62 to the userentity onwards, up to the user entity 10, whether or not the user entityuses the access opportunities during intervals 60 to handover itselffrom one base station to the next, or, from a different perspective, itis up to the user entity to exploit these opportunities provided thatother external circumstances did not prevent user entity 10 fromexploiting these opportunities because, for instance, the prediction ofroute 52 of the forecast on the basis of the event of UE 10 enteringarea 56, turned out not to be correct.

For the sake of completeness only, it should be noted that the timeconsumed by querying the base stations of set 50 and obtaining theanswers up to sending schedule 62 may be negligible compared to thetemporal length 54 within which the one or more expected times t_(i) aredistributed. The schedule 62 may define a certain temporal access 60 byindicating, for instance, its start time t^(x) _(start) wherein an endof the temporal access interval 60 could implicitly be defined by amaximum length of each interval 60. In other words, the respective basestation 14 _(x) could close the access opportunity after a certain timeafter t^(x) _(start). The temporal end of interval 60 could beindicated, too, however in the schedule 62.

As described later on, the query sent from base station 12 to the targetbase stations of set 50 may possibly contain one or more currentidentifiers using which the user entity 10 is identified in the cellularnetwork such as, for instance, an identifier via which the user entity10 is identified in the core network 34 such as in the MME 32. Inparticular, the query could additionally or alternatively inform thebase stations of set 50 about the context data of user entity 10. On theother hand, performing the preemptive preparation of the handover asjust described could also additionally involve sending a schedule 66such as a copy of schedule 62 from base station 12 to core network 34such as MME 32 within core network 34 so as to schedule a redirection ofpackets of one or more communication paths for communication sessions ofthe user entity 10 over the cellular network 24 and the user entity 10so that the packets are distributed to each base station of set 64depending on the respective temporal access interval 60 of therespective base station in set 64. In other words, MME 32 or the corenetwork 34 would be able to plan, at an early stage; namely, at the timeof receiving schedule 66, a distribution of inbound packets arriving,for instance, from the external network, to base stations among set 64other than the base station via which the user entity 10 is currentlyconnected to cellular network 24. Packets, for instance, which arelikely to be buffered too long at a certain base station of set 64 andcannot be transmitted from that base station to the user entity 10before the expected handover from that base station to the next basestation of set 64, may be forwarded by core network 34 or MME 32,respectively, to the next base station of set 64 according to thesequence of expected times covered by the respective temporal accessintervals 60. The cellular network 34 would, first, not have to wait forsuch redirection until the handover actually takes place on behalf of UE10 actually using the one or more access parameters it has been providedwith by way of schedule 62.

It should be noted that the cardinality of the set 50 and thecardinality of set 64 or the cardinality of either of these sets mightbe greater than 1. Generally, however, both may be 1, 2. As to thefuture start time 70 indicated in schedule 62 to indicate the start ofthe respective temporal access interval 60, it is noted that the samemay be indicated by quantization indices or in seconds or the like.

It should have become clear from the above, that, if the prediction thatformed the reason for the preemptive preparation of a handover is good,the UE 10 is likely to handover from base station 12 to the target basestation for which the temporally-nearest temporal access interval 60 isindicated in schedule 62. That is, UE 10 will use the one or more accessparameter 66 for this target base station which would, in the exampleillustrated in FIG. 4, for instance, be the base station 14 _(a), duringtemporal access interval 60 and thus, would perform or activate thehandover preemptively prepared as described so far. This base station 14_(a) would then inform base station 12 about the user entity havingaccessed the cellular network 24 via the base station 14 _(a) andtriggered by this information, base station 12 would cut its connectionto UE 10, while core network 34 would be informed by base station 14_(a) with, triggered thereby, redirecting a cellular network internalsub-path of each of a set of one or more communication paths of one ormore communication sessions running via the cellular network 24 and theuser entity 10, from base station 12 to base station 14 _(a). Further,resources of the base station 11 via which the user entity 10 iscurrently or, better, has been so far, connected to the cellularnetwork, here base station 12, could be released such as one or morebuffers thereof managed by the base station for the one or morecurrently active communication sessions of UE 10. Base station 12 couldcut its connection to UE 10 and/or release its resources alternativelyin response to a signal sent from the core network indicating that thepath redirection has been performed responsive, in turn, to the notesent from target base station 14 _(a), which then assumes the now roleas source base station. In the same manner, the next handover betweenthis target base station, which is now the source base station, to thenext target base station of set 64 takes place.

Thus, with respect to FIG. 4, a cellular network 24 has been describedwhich supports a preemptive preparation of a handover for user entity10. Concurrently, however, the above description revealed a user entity10 for communication over a cellular network 24, wherein the user entity10 is configured to gain information on a predicted future route 52 ofthe user entity and inform the cellular network on the predicted futureroute 52. The UE could transmit a list or vector of coordinates, e.g.WGS84 coordinates, to the cellular infrastructure 24. UE 10 could dothis upon request from the base station 12, from a V2X server or inregular time intervals. It should be noted, however, as described above,the origin of the information on the predicted future route 52 may stemfrom an entity other than the user entity 10. The information on thepredicted future route 52 may be sent to cellular network 24, forinstance, as a set of pairs of time and coordinates of locations atwhich the user entity 10 is on the predicted future route 52, or asequence of coordinates of location sequentially traversed by the userentity along the predicted future route 52 such as locations which theuser entity traverses along the predicted future route 52 at a certaintemporal pitch of a constant pitch interval.

Further, however, the above description revealed the description of auser entity for communication over a cellular network 24, wherein theuser entity 10 is configured to manage a set of one or more preemptivelyprepared handovers. In this way, the user entity 10 not necessarilyinforms the cellular network on the predicted future route 52. Ingeneral, the user entity 10 could handover to more than one carrier. Theuser entity could, thus, perform the handover within the frame work ofdual connectivity, e.g. LTE+NR/5G, multi-RAT e.g. separate networks LTE,CDMA/UMTS, NR or carrier aggregation, e.g. handover to a carrier withlower frequency=better coverage or higher frequency=potential highercapacity or lower latency. Details and background in this respect areoutlined below. In any case, the user entity 10 may be able to manage aset of one or more preemptively prepared handovers; namely, thoseindicated in schedule 62 which user entity 10 receives from the cellularnetwork 24 and the source base station 12, respectively. From thereception onwards, i.e., substantially over the whole time interval 54,the user entity 10 continuously checks whether the schedule 62 becomesinadequate. For instance, the user entity recognizes that the userentity gets farther away from the predicted future route 52 because, forinstance, the user of the user entity 10 decided to take another waythan rule 52. In that case, user entity could inform the cellularnetwork 24 on the inadequateness so that, for instance, cellular network24 could inform the target base stations of set 64 thereabout so thatthe latter could render the reserved radio access resources associatedwith the one or more access parameters available for other userentities. As described above, the user entity could derive from theschedule 62 the temporal access interval 60 plus associated one or moreaccess parameter 66 per target base station within set 64 and then, fromthe reception of schedule 62 onwards, continuously decide on accessingthe cellular network 24 via any of this set 64 of target base stations;namely, any base station of the set 64 within a reach of which the userentity 10 currently is. Obviously, this decision is merely availableduring the temporal access interval 60 associated with a respectivetarget base station, annually using the one or more access parametersspecified in the schedule. The user entity 10 is able to perform ahandover or access of the cellular network using schedule 62, or performthe just described continuous decision thereabout, without obtainingcurrent permissions from the cellular network 24 on a case by casebasis, i.e., without obtaining current permission during time interval54. Schedule 52, instead, serves as a license for user entity to performeach handover during the respective time interval 60.

As described later on in more detail, user entity 10 may be configuredto perform the management of the set of one or more preemptivelyprepared handovers as outlined in schedule 62 with respect to one ormore wireless connections to the cellular network 24 of a set of currentwireless connections to the cellular network 24. For instance, userentity 10 could use aggregated carriers and perform the exploitation ofpreemptively prepared handovers with respect to one or more than onecomponent carrier of such aggregated carriers.

As should have become clear from the above, the user entity may be ableto resume connectivity to the cellular network after loss of theconnectivity using any of the set of one or more preemptively preparedhandovers despite a temporary loss of connection. For example, in ascenario where the UE lost connection due to a tunnel, UE 10 and thenext base station involved in the preemptive preparation of HOs maysimply resume the connection between using the preemptively prepared HO.

Although not described above so far, it should be noted that in additionto the description brought forward above with respect to FIG. 4, oralternatively thereto, a cellular network could be configured to followa third aspect of the present application. In particular, the cellularnetwork could analyze a predetermined set of cells 15 of base stationsaround the position of the user entity with respect to a set of possibleroutes leading away from the user entity's position to determine afavorite route among the set of possible routes in terms of connectivityto the user entity. For instance, a cellular network could query the set50 of target base stations with the set 50, however, covering more thanone route, i.e., a set of possible routes leading away from the currentuser entity's position. The target base stations of set 50 would, thus,be determined to cover all routes in the set of possible routes. Thetarget base stations of set 50 would answer the query and based on theseanswers, cellular network 24 could determine a favorite route out of allroutes in the set of possible routes in terms of connectivity; namely,the route alongside of which, for instance, all nearest base stationsindicated a possible access time interval 60 plus associated one or moreaccess parameters 66. For example, the favorite route could be the BestConnected Route from point-of-view of the user terminal UE, such as theroute providing highest QoS. The favorite route could be the BestConnected Route from base station point-of-view such as the route withthe least traffic or highest capacity/coverage/lowest delay/best userexperience/low overload likelihood. The cellular network 24 could informthe user entity 10 about the favorite route actively or upon request orpolling by the UE 10. For instance, currently serving base station 12could provide a download link, so that the UE 10 or its user can decideitself to update its route. In other words, base station 12 or cellularnetwork 24 could push this information to the UE. Alternatively, the UE10 could download or pull this information on the favorite route fromthe cellular network 24. Applications running on the user entity, forinstance, could use this information. By this measure, the user of auser entity, for instance, could be provided with this information suchas, for instance, via a display or a similar output device of the UE 10,and the user could decide, as the bearer of the user entity 10, to takethe favorite route in order to, for instance, enjoy a currentlydownloaded video without any stall event. The “user” should be, however,not be restricted to a human user. Imagine the UE to form an interfaceof a robot or other autonomous driving device where an interruption ofthe data connection could have tremendously negative and dangerousimpacts. Likewise, the recipient of a path recommendation could beanother device such as device responsible for, or cooperating in,determining the future route which the UE takes such as a trafficmanagement unit. The information about the possible routes could beprovided by the cellular network from outside. However, the cellularnetwork could determine the set of possible routes by itself or couldreceive this information on the set of possible routes from the userentity. That is, the cellular infrastructure 24 could recommend certainroutes based on the coverage, e.g. by indicating to the user, whichroute index provides the best coverage, e.g. top-m routes from thenetwork point-of-view. Analysis and information provision could beperformed within the source base station 12. That is, any base station11 could have this functionality. The functionality could, however, byrealized in other device of the cellular network 24.

The above embodiments could be used to achieve lower handover latencyand/or lower control signal overhead associated with handovers.

Current LTE Handover (HO) procedures have not been designed toaccommodate Ultra Reliable Low Latency Communications (URLLC) where theexisting average minimum HO is approximately between 40-50 ms [1]. As aresult, there is room to improve the efficiency of the overall HOprocess for 5G use cases, including low latency communications. This maybe done by using the embodiments described so far.

An efficient and rapid mechanism for performing handovers throughpredictive route information of the UE with varying mobility speeds maybe achieved using above embodiments. The advantage of the latter enablesreduced signaling overhead and latency when connecting to the subsequenttarget eNB(s)/gNB(s) for LTE and New Radio (NR) network architectures.This may be performed by UE signaling the pre-allocated target cellparameters 66 used to connect to the target eNB/gNB before the actual HOprocess. FIG. 6 provides an overview of a Predictive-HO (P-HO) scheme inthe LTE framework.

A preemptive decision will have to be triggered before the actual HOoccurs in order for the Source/Anchor eNB/gNB 12 to signal the UE 10with the target eNB/gNB parameters 66 (e.g. RRCConnectionReconfigurationincluding the mobilityControllnfo message), examples of which areoutlined in the table shown in FIG. 7.

In even other words, the embodiments described so far enable anefficient mechanism for predictive handovers in a NR network with Npredicted target gNBs.

The following aspects may be supported (cp. FIG. 4 and FIG. 6):

-   -   1) Initiate a HO preparation to N-target eNBs 64 along a        predicted path 52 and UE pre-allocated signaling using triggers        initiated by the:        -   a. the source gNB or anchor gNB 12 (Network Controlled),        -   b. UE 10 triggered,        -   c. a novel centralized entity 80 in the radio access network            24, e.g. central baseband unit (CBBU) with a central Radio            Resource Management (RRM) (Network Controlled).    -   2) Efficient N-hop predictive context forwarding using network        signaling sent from        -   a. a source or anchor-gNB 12 to N target-gNBs 64,        -   b. an anchor gNB 12 within a RAN            paging/tracking/notification area such as 40 to N new or            potentially new anchor eNB within a new RAN            paging/tracking/notification area,        -   c. a central baseband unit 80 and/or to N new or potentially            new central baseband units,        -   d. a source gNB 12 or CBBU 80 to the UE 10 in preparation of            a HO process.

In particular, the NW or UE 10 can trigger the initiation of a N-hopPredictive Handover (P-HO), according to the RRC State. The P-HOprocedure is a set of configuration parameters 64 of a set 64 of targetcells along a predicted route 59 that are signaled to a UE 10, before aHO actually takes place. The UE 10 can, with the aid of certainavailable side information (CAM Messages containing time, 2D and 3Dlocation reporting, location vectors, location coordinate intervals,journey route, flight plan etc.) trigger the source/anchor eNB 12 toperform a P-HO. Two options are considered for driving the P-HO:

-   -   1. In RRC Connected (LTE)/Active (NR) Mode: The source/anchor        eNB 12 or the CBBU 80 in case of CU/DU (central unit/distributed        unit) split) initiates and performs the P-HO.    -   2. In Lightly Connected (LTE)/Inactive (NR) Mode: The UE 10        autonomously initiates the request for the relevant P-HO        configuration parameters including the predictive context        forwarding to all relevant target eNBs/gNBs.

Therefore, the source eNB or centralized entities (e.g., CRRM, CBBU,MME) can initiate the multiple predictive HO preparation for N≥1 targeteNBs 64 along the predicted UE trajectory 52. This scheme avoids theneed to re-initiate the HO preparation phase once the UE passes througheach of the expected target cells since all the used resources have beenpre-allocated. The resulting P-HO scheme aims to reduce signalingoverhead and latency, once information about the predicted route 52 hasbeen established. The N expected target eNBs 64 will expect the UE 10 toreach its cell within a pre-defined interval 60 (valid time interval)based on the initial setup time t₀ of the N-hop predictive HO procedureand a UE mobility type (e.g. high or low speed). If the UE 10 abruptlychanges trajectory or remains stationary at a particular target cell,then all target eNBs/gNBs 64 identified during the P-HO procedure canrelease the pre-allocated resources via a timeout.

An example sequence diagram for a NW or UE driven P-HO is shown in thesequence chart in FIG. 8. The embraced portion 90 indicates thesignaling scheme specific for the P-HO scenario. The P-HO procedure istriggered by the centralized entities such as 80 or source eNB/gNB 12when the UE 10 is either in the proposed active (NR) and normal RRCconnected states (LTE) as shown in the state diagram (FIG. 3) [3]. Whenthe UE 10 is in the lightly connected mode, prediction information basedon the P-HO can enable the UE to autonomously transition betweeneNB/gNBs cells belonging to different paging areas as described fartherbelow. In order to perform the used RRC Reconfiguration between eachcell, the UE can transition from a normally connected state to a lightlyconnected state. As a result, the UE can be in a low power lightlyconnected state and still perform the P-HO.

Messaging Step Overview of FIG. 8

-   Message 2: This trigger can be initiated in the source eNB (or    centralized unit) when the UE is in RRC connected/Active mode (in    which there is no additional message. Alternatively, the P-HO can be    triggered by the UE autonomously in lightly connected/inactive mode    as part of the measurement report.-   Message 3: This is a distributed message by the source eNB/gNB    requesting the availability of resources from each target eNB/gNB    (multiple HO preparation) together with the UE context to be    transferred.-   Message 4: Container with ACKs from respective target eNBs/gNBs with    available resources.-   Message 5: UE message with the used signaling parameters for the    target eNBs/gNBs.

FIG. 9 is a further illustration of the aforementioned messages using aCentralized Unit/Distributed NR Architecture. The signaling flows of themessages correspond to the proposed messages in FIG. 8.

Key Procedures of the P-HO:

A more detailed exemplary message description is presented below:

-   Message 2: The Source eNB/centralized unit or UE can trigger the    P-HO process. From the source eNB/centralized unit perspective the    trigger can occur by monitoring the UE when in connected mode and    then executing a P-HO. In relation to the UE, information about the    predicted route can be directed by the UE itself, enabling it to    autonomously move between paging areas in lightly connected mode    using the onboard prediction data. The UE can signal the following    messages to the source eNB within the measurement report:    -   CAM messages,    -   Speed, acceleration, velocity, 2D and 3D location reporting,        etc.    -   Route information, GPS information, flight plan    -   Traffic information, etc.

Example Syntax: UE-aided-P-HO-IE

IE/Group Name Description Message Type [4] “Identifies the message beingtransmitted, e.g. Handover Resource Allocation, Path Switch Request”[12] CAM-Aided-Route-Prediction The list of data elements in [14] AnnexA, e.g. Acceleration Control, CourseofJourney, Reference PositionPath-target-eNB-ID-List If available the positions or ID of target eNBsalong the predicted route RRC-Connect-Time RRC connect period of currentcell RouteInfo/FlightPlanInfo 2D and 3D location vector of UE, UEDirection, course location points along a UE route

-   Message 3: The P-HO request message via S1/X2 requests resource    availability from potential target eNB/gNBs about a predicted    handover from a specific UE. It can contain information about the    user such as expected arrival time, unique IDs, context and security    information and expected level of service requirements.

Additionally, the context of the UE can be pushed to all target eNBs. Anexample of this setup S1 message could include: P-HO-REQUEST-IE(Direction: source eNBs→Target eNBs)

IE/Group Name Description Message Type [4] Identifies the message beingtransmitted, e.g. Handover Resource Allocation, Path Switch RequestHandover Type[4] Indicates the type of Handover at the source eNB, e.g.IntraLTE, LTEtoUTRAN eNB List to be setup Identifies a list of targeteNBs MME-UE-S1-AP-ID[4] “Uniquely identifies the UE association over theS1 interface within the MME.” [12] eNB UE S1AP ID [4] “Uniquelyidentifies the UE association over the S1 interface within the eNB.”[12] Predicted UE Behavior Defines the future behavior of the UE withpredictable activity with predicted info, to assist future eNBs indetermining the optimum RRC connection time. UE Context Transfer The UEcontext is pushed to all Target nodes based on the prediction. UEMobility Type Low, Medium, High speed

-   Message 4: The response from the target eNB can acknowledge or deny    the request via S1/X2 to the requesting source eNB/centralized unit    using a ACK/NACK message. The decision is based on the outcome of    the admission control and availability of resources. Once the target    eNB acknowledges the request it has prepared resources for the    potential new UE, has stored the new context and configured the    lower layer protocols. An example of such a message from each target    eNB is given as:    -   P-HO-REQUEST-ACK-IE (Direction: Target eNBs→source        eNB/Centralized Unit)

IE/Group Name Description Message Type [4] “Identifies the message beingtransmitted, e.g. Handover Resource Allocation, Path Switch Request”[12] eRABs-Admitted-List [4] “HO Request ACK message is sent by theTarget eNB to inform the MME about the prepared resources of the Targetsuch as E- RABs Admitted List. Hence the E-RABs those could be admittedin the target are refered as E-RABs Admitted List.” [12].MME-UE-S1-AP-ID [4] “Uniquely identifies the UE association over the S1interface within the MME.” [12] eNB UE S1AP ID [4] “Uniquely identifiesthe UE association over the S1 interface within the eNB.”[12]

-   Message 5: The table shown in FIG. 7 is a summary of the used UE    signaling parameters that would be sent over the air to the UE    originating from the eNB/gNB. The security keys of the target cells    would use an additional layer of encryption, if they are to be    pre-allocated. The RNTI and RACH Preambles can be pre-allocated    according to the mobility type, thus eliminating the need for the UE    to acquire these parameters each time when transitioning between the    target cells. The UE could keep its identity across several cells,    depending on whether the UE is in high mobility. One approach could    be that the UE has a single ID within the RAN paging/notification    area (e.g. selected by the anchor eNB where the UE entered the RAN    paging/notification area or selected by a central node e.g. CRRM,    CBBU, MME) denoted by the Unique-UE-ID element.    -   The RAN (source eNB/centralized unit) may differentiate between        three mobility types (e.g. low, medium and high mobility). Low        and medium mobility types would get a cell specific C-RNTI,        while the high mobility types of UEs can keep their identities.        The target eNB would then know which UE ID to lookup, from the        UE context already received in message 3. The SL configuration        can also be pre-allocated to enable V2V communications. If the        request is granted and the handover is prepared this message        includes parameters used for the UE connect to Target eNBs.    -   The timeout indicator would be set at the source eNB depending        on whether the P-HO was NW or UE triggered, and shared with the        multiple target eNBs. The UE can notify the target eNBs via        uplink signaling and if the UE does not enter the cells of the        target eNBs within the time used, the pre-allocated resources        are released and the fallback would be the traditional HO        procedure.    -   A common RACH preamble management and/or common RACH resource        management within the RAN paging/notification area would be        envisioned. A high mobility UE would transition rapidly from one        eNB to another and therefore may use the same preamble, across        multiple target eNBs. It would then entail the notion of a        common RACH resource pools across eNBs in order for the same        RACH signal to be sent to multiple target eNBs along the route.        Multiple target eNBs might then be able to decode the signal,        which entails the formation of a common RACH resource pool. This        highly depends on the RACH load and the RACH resource reuse.        Since multiple cells share resources it might need to be        operated at lower load decreasing efficiencies due to lower        resource reuse.

P-HO User Data Forwarding, in case of out-of-coverage scenario may bedone as follows: In the event that the UE loses coverage and has a RadioLink Failure (RLF) during the P-HO process with source eNB-1, we havethe out-of-coverage scenario shown in FIG. 10. The UE attempts an RRCconnection re-establishment to the target eNB given that it has alreadyacquired the signaling parameters to connect with the target eNB.Redundant data forwarding could be applied to a centralized unitarchitecture.

Step/Description 1: RRC connection re-establishment: Enablingsynchronization and timing advance using the prediction informationalready at the UE. This procedure can be initiated with the preparedRACH preambles and C-RNTI.

Step/Description 2.1: Prior to timeout with the source eNB, the corenetwork has already forwarded redundant data via the centralized unit tothe next target eNB based on information from the predictive HOprocedure. This redundant data is forwarded to the target eNB, subjectto the initiation of the P-HO process.

IE/Group Name Description Message Type [4] “Identifies the message beingtransmitted, e.g. Handover Resource Allocation, Path Switch Request”[12] X2 TNL Configuration Contains the P-HO related information. Info[4] Core Data Forwarding Forwards the redundant data as initiallytransmitted to the source eNB. MME-UE-S1-AP-ID-SeNB “Uniquely identifiesthe UE association over the S1 interface within the MME.” [12]

Step/Description 2.2: The UE can transmit a last packet ACK sequencenumber to the target eNB, to resume data forwarding from the last knowntimeout of the RRC connection with the SeNB.

IE/Group Name Description Message Type [4] “Identifies the message beingtransmitted, e.g. Handover Resource Allocation, Path Switch Request”[12] X2 TNL Configuration Contains the P-HO related information. Info[4] UE Data Forwarding Sends ACK and forwards the SN number.

In Dual-connectivity mode UE P-HO could be used as well.

Dual-connected (DC) P-HOs enable URLLC services of mobile UEs andtherefore can fulfill the high reliability requirement. Predicted UEroute information can also aid in seamless handover of UEs, which are indual-connectivity mode, i.e. simultaneously connected to two eNBs, themaster eNB and secondary eNB. This is particularly applicable toscenarios where a mobile UE travels across a number of small cellswithin a macro cell environment, e.g. dense urban scenario. A group ofsuch small cells belong to a secondary cell group (SCG). DC enabled HOscan result in zero interruption due to the availability of at least oneconnected link at all times. The novel claim consists of the wayDual-connectivity can be initially leveraged to enable the master eNB toperform the P-HO for multiple small cells (secondary eNBs) allowing theUE to move across the small cells in a seamless fashion reducingoverhead in standard HO signaling as described in E1. The procedure isas follows:

-   -   1. The master eNB initiates the P-HO process (according to the        source driven P-HO procedure) by receiving the SCG information        which includes the parameters in Table 1 for each small cell.    -   2. The master eNB then provides this information to the UE (via        a RRC Reconfiguration message) with all the used P-HO        information for each small cell along the predicted route (See        Table 1).    -   3. The master eNB can then terminate dual-connectivity, allowing        the UE to have a single Uu connection with each small along the        predicted route with the advantage that the HO has already been        prepared, allowing a RRC Reconfiguration with each small cell in        a seamless fashion.

The following description now attends to a description of the secondaspect of the present application which pertains to the handling of userentities in a non-active mode in an efficient manner by the usage of aso-called “tracking/paging area”. Again, the description of this aspectand embodiments thereof starts with a type of presentation or overviewso that the underlying problem with non-active UEs is clear and theadvantages resulting from the embodiments described later on. Thefollowing overview is, however, partially also an extension of theintroductory portion with respect to the description and presentation ofthe embodiments concerning the first and third aspects of the presentapplication described above.

Mobility enhancements in lightly connected or inactive mode wererecently developed. The state machine in current control plane protocolsin cellular wireless mainly support two modes: the idle mode and theconnected mode. In the idle mode, the UE monitors the control channel(PCH) according to a discontinuous reception (DRX) cycle. While in theidle state, the MME is responsible for the monitoring the UE. In theconnected mode, the UE is connected to a known cell and can perform datatransfer to and from the device. While in the connected mode/activestate, the corresponding eNB is responsible for monitoring the UE.

HOs are performed when the UE is in the RRC connected mode. Currently indiscussion is the introduction of a new mode, which is referred to aslightly connected (in LTE) or as inactive state (in 5G new radio (NR)),which should increase signaling efficiency, also for new services. Inthis state, the UE is responsible for transferring into idle orconnected states. The lightly connected UEs enter into legacy behaviorin RRC connected via RRC procedure including three messages (i.e.request, response and complete). In the lightly connected state, the S1connection for this UE is kept and active, and a new signaling schemefrom the UE could be introduced, in order to optimize handovers andimprove network performance though movement predictions. FIG. 11 is anexample of the lightly connected state mode of operation as proposed in[3].

RAN Paging/Notification Area and Tracking Area is used to tracknon-active UEs. Paging is used for network-initiated connection setupwhen the UE is in the idle state (RRC IDLE), see [5]. This shallindicate to the UE to start a service request. Since the location of thedevice is typically not known on a cell level, the paging message istypically transmitted across multiple cells in the so-called trackingarea. These tracking areas are controlled by the MME. The UE informs thenetwork via tracking area updates (TAU) of its location with thenetwork. To reduce signaling traffic, a UE does not need to initiates aTAU if it enters a tracking area which is included in its tracking arealist (TAL). See FIG. 2.

As to NR Architecture, two proposed architecture types for NR areproposed, viz. Centralized Unit (CU) Architecture or Distributed Unit(DU) Architecture as shown in FIG. 13.

Regarding V2X System Architecture, one of the main modes of operation inV2X consists of the broadcast architecture and serves as exampleapplication of the proposed P-HO scheme.

As to Broadcast V2X Architecture, the high-level V2X broadcastarchitecture is shown in FIG. 14 with a new additional entity known asthe V2X application server [8].

The core functionality V2X Application Server is out of scope of 3GPP[8], and an overview of the role of the Application server has beendefined by the ITS. According to the definition in [8], the Applicationserver aggregates inputs from several sources including the vehicles onthe road, road side units as well as external information from variousother network entities. The Application Server then correlates thisinformation based on time, location and incident to develop a betteridea regarding the state of traffic. Once the information has beenconsolidated and processed it then has to decide in which information ithas to disseminate to other vehicles in a geographic area [9]. Currentlythe V2X application server has the following specifications according to3GPP, which fall in line with ETSI's proposal [8]:

-   -   Ability to receive uplink data from the UE over unicast.    -   Delivering data to the UE(s) in a target area using Unicast        Delivery and/or MBMS

Delivery.

-   -   Mapping from geographic location information to appropriate        target MBMS Service

Area ID (SAI(s)) for the broadcast.

-   -   Mapping from geographic location information to appropriate        target 3GPP E-UTRAN

Cell Global Identifier (ECGI(s)) for the broadcast.

-   -   Pre-configured with Local MBMS (L.MBMS) information (e.g. IP        multicast address, multicast source (SSM), C-TEID).    -   Pre-configured with L.MBMS's IP address and port number for the        user-plane.

In order to minimize delays between RAN and V2X infrastructure, the V2Xentities can be grouped into a eNB type Road Side Unit (RSU). This RSUcan be deployed directly at a eNB, similar to edge-cloud computing, e.g.via local IP breakout interface (LIPA). This enables faster predictionof the HO process. See FIG. 15.

Dual-connectivity (DC) was included as part of small cell enhancementsin LTE and offers several advantages which include [10]:

-   -   Increased UE throughput at the cell edge,    -   Increase in robustness for UE mobility,    -   Reduction in signaling overhead toward the core due to frequent        HO.

A UE can be connected to a Master eNB and Secondary eNB but can haveonly one RRC connection with the Master eNB. In a V2X scenario, DC canenhance seamless or zero interruption HO between various eNBs along apredicted route, by ensuring guaranteeing one active/inactive. The datasplit in the User-plane can take place at the bearer or packet level asshown in FIGS. 16 and 17 [10]

“To initiate the HO, the source eNB sends a HO Request on X2. The HORequest needs to be modified to indicate that this is a dualconnectivity HO as opposed to a traditional HO. The goal of the HO is tohand over a subset of the DRBs to the target eNB. Thus, we will need toaugment the HO request message to specify which bearers are to be handedover. Currently, the UE context includes information on the bearers thatare assigned to the source eNB. For dual connectivity, the UE contextwill need to specify which of its bearers are mapped to the target eNB.

The target eNB will indicate which bearers it is willing to accept inthe HO Request ACK. As in the current HO procedure, bearers that are notaccepted will be dropped. The target eNB sends the DL allocation andRRCConn Reconf with mobilityControlInformation to the source who sendsit to the UE. SN status transfer and data forwarding will proceed forthe bearers that are to be transferred. The UE will start RACH on one ofits radios while maintaining regular communication of all bearers thatremain on the source eNB.

If the handover is successful, the UE sends RRC Conn Reconf Complete asusual. Upon HOF, a new RRC message is sent to the source eNB on itsassociated UE radio to indicate the failure. The source eNB can assistthe UE by either accepting a connection from radio #2 or by preparinganother eNB to do so.

If the HO was successful, the target eNB will send a path switch Requestto the MME on S1 requesting its assigned bearers. The MME will sendModify Bearer request to the Gateway. Finally, the target eNB updatesits UE Context and sends a UE Context Update to the source eNB over X2.The source eNB updates its UE Context and releases resources associatedwith the HO.” [12]

It should have become clear from the brief introduction put forwardabove, the concept of managing a tracking/paging area for some userentity reduces the burden on the side of the cellular network tocontinuously reserve radio resources for user entities for which one ormore communication sessions are active, but for which the one or morecommunication session does not involve a continuous transmission ofpackets. Thus, it is sufficient if the cellular network keeps track ofwhere the UE is at least approximately; namely, within sometracking/paging area, so that packets addressed to the UE may beforwarded to the one or more base stations within this tracking/pagingarea, and if the base stations within the tracking/paging area know thecontext data of the UE. The concept exploited in some of the embodimentdescribed with respect to active UEs and the preemptive preparation ofhandovers as used in some of the embodiments described above, is nowreused in order to more efficiently deal with non-active UEs; namely, inthat a schedule of a time-varying tracking/paging area is introducedand/or a tracking/paging area is determined depending on a predictedfuture route of the user entity.

In order to explain embodiments of the present application with respectto this aspect, reference is made to FIG. 19 which reuses some of thereference signs already used previously; namely, with respect toentities that assume the same or a similar task within the overallcommunication network.

In particular, FIG. 19 shows a cellular network 24 which is, asdiscussed with respect to FIG. 4, composed of a plurality of basestations 11 spread so as to cover with their associated cells 15 acertain region or geographical area, wherein the base stations 11 serveUEs within their cells in that the same perform the wirelesscommunication with the UEs within their cells. The base stations 11 areconnected via some interface 28 with the core network 34 of cellularnetwork 24. This core network 34 in turn, may have an interface towardsan external network 42. With respect to activated UEs, i.e., UEs whichare currently connect to the cellular network 24 via a current sourcebase station, the behavior of cellular network 24 and the UEscommunicating via cellular network 24 of FIG. 19 may be as describedwith respect to FIG. 4 or, optionally, in accordance with the currentsolutions discussed above with respect to FIGS. 1 to 3. The cellularnetwork 24 of FIG. 19, however, is configured to establish for apredetermined user entity 10 a schedule of a time-varyingtracking/paging area spanned or defined by a time-varying set of one ormore base stations or made-up by the cell(s) of the set of one or morebase stations. In order to explain this in more detail, reference ismade to FIG. 20. FIGS. 19 and 20 assume that the base stations 11 arespatially pre-clustered into so-called “paging areas” 90. Four suchclusters or spatially-neighboring base stations 11 are exemplarily shownin FIG. 19. It should be noted, however, that this clustering is notmandatory for the present embodiment. As shown in FIG. 20, the cellularnetwork 24 determines, at some time instant t₀, for a UE 10, atime-varying tracking/paging area. The time instant t₀ might, forinstance, be initiated by UE 10 which decides to switch from an activemode to an intermediate mode of low activity, the details of which aredescribed and exemplified in more detail below. The tracking/paging areais, at each time instant, an area served or spanned by a set of one ormore base stations, but this set varies in time. Its determinationoccurs at time instant t₀ based on some sort of prediction similar tothoughts which led to set 50 in FIG. 5. For instance, thetracking/paging area may be defined to follow a predicted future route52 of UE 10, i.e., to follow the position the UE 10 has predicted toassume in route 52. The outcome of such determination is shown in FIG.20 as a schedule 100. In particular, schedule 100 defines, for each timeinstant within some time interval 102 which follows time instant t₀, theset of one or more base stations 11 which form the tracking/paging area,i.e., set 104. In FIG. 20 it is exemplified that schedule 100 indicatesthe set 104 in units of clusters 92, but this might be solveddifferently. In particular, schedule 100 indicates this set forconsecutive partial intervals 106, into which the time interval 102 issub-divided. That is, for each such partial interval 106, schedule 100indicates the set 104 of base stations 11 which make up thetracking/paging area. Alternatively, the UE 10 is intermittentlyinformed on the time-varying tracking/paging area by way of messagesintermittently updating the set of base station cells defining the area104.

The cellular network 24 then sends the schedule 100 or messagesintermittently updating area 104 to the user entity 10 which, thus, isable to continuously check whether the UE 10 leaves this time-varyingtracking/paging area defined by the time-varying set of one or more basestations 104 or not. As long as the UE does not leave the time-varyingtracking/paging area, the UE is within an area within which the cellularnetwork 24 expects the UE 10 to be. As long as the UE 10 does not wishto initiate an uplink communication and to switch to active mode, the UE10 needs to do nothing. The cellular network 24, in turn, takes theappropriate measures to fulfill tasks which seek to reflect the factthat the tracking/paging area is changing over time as scheduled inschedule 100. In particular, the cellular network 24 provides each basestation of set 104, i.e., each base station currently within the set 104of base stations which define the tracking/paging area, with contextdata of UE 10 so that these base stations are aware, for instance, ofthe UE's 10 subscriber data currently active one or more communicationsessions, one or more IDs used by the cellular network 24 to identify UE10 and distinguish UE 10 from other UEs and/or other UE specific data.Further, cellular network 24, itself, uses schedule 100 so as to searchfor UE 10 whenever an inbound or downlink packet of one of one of moreactive communications sessions arrives at the core network 34 addressedto UE 10. In particular, the cellular network 24 then looks up inschedule 100 which set 104 of base stations currently makes up ordefines the tracking/paging area and informs via these one or more basestations that the UE 10 should connect to the cellular network 24 so asto be able to receive this packet. The control signaling overhead iskept low as the UE is within the time-varying tracking/paging area andthe base station within the cell 15 of which the UE 10 currently is,belongs to the set 104 defining this tracking/paging area and this basestation already has at hand the context data of UE 10.

It should be noted that, according to an alternative embodiment, thecellular network of FIG. 19 does not form a schedule 100 of atime-varying tracking/paging area. Rather, as depicted in FIG. 21,according to this alternative, the cellular network 24 uses the gainedknowledge about the predicted future route 52 so as to appropriatelyselect the set 104 of one or more base stations which define thetracking/paging area. As long as the UE is within this area 104 whichhas precisely been predicted using predicted future route 52, controlsignaling overhead on the side of the UE which could negatively impactthe power consumption of UE 10, may be avoided. In the example of FIG.21, cellular network 24 sends to the UE 10 the set 104. In bothalternatives discussed above with respect to FIGS. 20 and 21, the userentity 10 is a user entity for communication over cellular network 24and the user entity 10 is configured to continuously check whether it isstill in the tracking/paging area defined by the set 100 of one or morebase stations or whether the user entity has left the same. In case ofleaving, the user entity 10 sends a tracking/paging area update messageto the cellular network 24 which, in turn, then re-initiates thedetermination of the tracking/paging area according to FIG. 20 or FIG.21, respectively. In case of receiving schedule 100, user entity 10 isable to check this schedule 100.

Thus, the above examples of FIGS. 19 to 21 reveal that it is possible torealize and autonomous UE handover decision in RRC inactive state for NR(in LTE called lightly connected) assuming the new context alreadyexists in the new node (already received in the new node because of thepredictive context forwarding). In other words, these embodiments enablea lightly connected mode of the UE with efficient paging usingprediction information.

Efficient Paging using prediction information in Lightly Connected Modeas shown in FIG. 19 entails the update of the centralized unitinformation and the Tracking Area Identifier (TAI) List of the variousRAN paging/notification areas using the predicted route information ofthe UE when in RRC lightly connected mode (RRC Idle mode not precluded).The UE traditionally receives a TAI list when initially attaching to asource eNB in the LTE network. When the UE travels in a Tracking Areanot contained in the TAI list, the UE sends a Tracking Area Update (TAU)informing the MME (core network) about its position. In order to enableto efficient paging using predicted route information, another solutionis proposed whereby the UE does not require the transmission of updatesto the anchor eNB or centralized unit when the UE changes RANpaging/notification areas:

1. The source/anchor eNB or centralized unit provides a near completepredicted RAN paging/notification area list (pPAI) list to the UE uponconnection establishment, corresponding with the predicted route of theUE, avoiding the need to page multiple cells of the same paging area(See FIG. 19) to locate the UE, thus reducing paging overhead. Accordingto FIG. 19, the UE would receive a pPAI={PA1, PA2, PA3} corresponding tothe predicted route. 2. To further increase paging efficiency in termsof finer granularity, another list containing the Target eNB IDs couldalso be provided. For example the target eNB list could contain,TeNBI={eNB-1, eNB-3, eNB-4, eNB-5, eNB-7} as seen in FIG. 19. When a DLmessage is waiting to be received in lightly connected mode, the anchoreNB or centralized unit need not page the PAs but rather the individualeNBs in the TeNBI list.

3. In the event, that the UE route abruptly changes the route and movesto a PA not on the pPAI, e.g. PA4 in FIG. 19, the UE notifies the anchoreNB or centralized unit using a paging area/RAN notification area update(PAU/RNAU). An example of additional predicted paging message parametersis shown in Table 1:

TABLE 1 Example messages for predictive paging IE/Group Name DescriptionUE-Paging-Area-ID “This IE represents the Identity with which the UE ispaged.” [12] pPAI-List TA list corresponding to predicted routeTeNBI-List-ID Identifiers of Target eNBs along predicted route

Thus, the above-described embodiment, inter alias, enabled a preemptiveUE signaling based on predictive UE route information to perform afaster HO. Again, it is noted that this might be used also in UEs whichare in a dual-connectivity mode. High reliability HO by using RRCdiversity using route prediction and dual-connectivity mode is feasible.All the above embodiments can be applied to wireless communicationsystems, e.g., cellular, wireless or meshed wireless networks as well aswireless ad-hoc networks.

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method, where a block or device corresponds to amethod step or a feature of a method step. Analogously, aspectsdescribed in the context of a method step also represent a descriptionof a corresponding block or item or feature of a correspondingapparatus. Some or all of the method steps may be executed by (or using)a hardware apparatus, like for example, a microprocessor, a programmablecomputer or an electronic circuit. In some embodiments, one or more ofthe most important method steps may be executed by such an apparatus.

Depending on certain implementation requirements, embodiments of theinvention can be implemented in hardware or in software. Theimplementation can be performed using a digital storage medium, forexample a floppy disk, a DVD, a Blu-Ray, a CD, a ROM, a PROM, an EPROM,an EEPROM or a FLASH memory, having electronically readable controlsignals stored thereon, which cooperate (or are capable of cooperating)with a programmable computer system such that the respective method isperformed. Therefore, the digital storage medium may be computerreadable.

Some embodiments according to the invention comprise a data carrierhaving electronically readable control signals, which are capable ofcooperating with a programmable computer system, such that one of themethods described herein is performed.

Generally, embodiments of the present invention can be implemented as acomputer program product with a program code, the program code beingoperative for performing one of the methods when the computer programproduct runs on a computer. The program code may for example be storedon a machine readable carrier.

Other embodiments comprise the computer program for performing one ofthe methods described herein, stored on a machine readable carrier.

In other words, an embodiment of the inventive method is, therefore, acomputer program having a program code for performing one of the methodsdescribed herein, when the computer program runs on a computer.

A further embodiment of the inventive methods is, therefore, a datacarrier (or a digital storage medium, or a computer-readable medium)comprising, recorded thereon, the computer program for performing one ofthe methods described herein. The data carrier, the digital storagemedium or the recorded medium are typically tangible and/ornon-transitionary.

A further embodiment of the inventive method is, therefore, a datastream or a sequence of signals representing the computer program forperforming one of the methods described herein. The data stream or thesequence of signals may for example be configured to be transferred viaa data communication connection, for example via the Internet.

A further embodiment comprises a processing means, for example acomputer, or a programmable logic device, configured to or adapted toperform one of the methods described herein.

A further embodiment comprises a computer having installed thereon thecomputer program for performing one of the methods described herein.

A further embodiment according to the invention comprises an apparatusor a system configured to transfer (for example, electronically oroptically) a computer program for performing one of the methodsdescribed herein to a receiver. The receiver may, for example, be acomputer, a mobile device, a memory device or the like. The apparatus orsystem may, for example, comprise a file server for transferring thecomputer program to the receiver.

In some embodiments, a programmable logic device (for example a fieldprogrammable gate array) may be used to perform some or all of thefunctionalities of the methods described herein. In some embodiments, afield programmable gate array may cooperate with a microprocessor inorder to perform one of the methods described herein. Generally, themethods may be performed by any hardware apparatus.

The apparatus described herein may be implemented using a hardwareapparatus, or using a computer, or using a combination of a hardwareapparatus and a computer.

The apparatus described herein, or any components of the apparatusdescribed herein, may be implemented at least partially in hardwareand/or in software.

The methods described herein may be performed using a hardwareapparatus, or using a computer, or using a combination of a hardwareapparatus and a computer.

The methods described herein, or any components of the apparatusdescribed herein, may be performed at least partially by hardware and/orby software.

While this invention has been described in terms of several embodiments,there are alterations, permutations, and equivalents which will beapparent to others skilled in the art and which fall within the scope ofthis invention. It should also be noted that there are many alternativeways of implementing the methods and compositions of the presentinvention. It is therefore intended that the following appended claimsbe interpreted as including all such alterations, permutations, andequivalents as fall within the true spirit and scope of the presentinvention.

LIST OF ACRONYMS AND SYMBOLS

In addition, reference is made to 3GPP TR 21.905: “Vocabulary for 3GPPSpecifications”.

-   eNB Evolved Node B (3G or 4G base station)-   gNB NR node=next Generation NB (5G base station)-   LTE Long-Term Evolution-   NR New Radio-   UE User Equipment (User Terminal)-   HO Handover-   P-HO Predicted Handover-   RRC Radio Resource Control-   MME Mobile Management Entity-   V2V Vehicle-to-Vehicle-   V2X Vehicle-to-infrastructure-   SeNB Secondary eNB-   MeNB Master eNB

REFERENCES

-   [1] S. Sesia, I. Toufik, and M. Baker, LTE The UMTS Long Term    Evolution: From Theory to Practice, 2nd ed. Wiley, 2011-   [2] Alcatel Lucent, The LTE Network Architecture: A comprehensive    Tutorial, White Paper, pp. 1-26, 2009-   [3] Qualcomm, Design details for light connection model A, TDoc    R2-168345-   [4] LTE; Evolved Universal Terrestrial Radio Access Network    (E-UTRAN); S1 Application Protocol (S1AP), TS 136 413 V12.3.0 (2014    September), pp. 114-   [5] E. Dahlman, S. Parkvall, J. Skold, “4G, LTE-Advanced Pro and The    Road to 5G”, Elsevier, 3^(rd) Edition, 2016-   [6] LTE; Evolved Universal Terrestrial Radio Access Network    (E-UTRAN); Overall Description, Stage 2, Release 14, TS 36 300    V14.1.0 (2016-12), pp. 96-   [7] 3GPP, “Study on New Radio Access Technology; Radio Access    Architecture and Interfaces (Release 14)”, Tech. Rep, TR 36.801    v1.0.0, December 2016.-   [8] Technical Specification Group Services and System Aspects;    Architecture enhancements for V2X services (Release 14), TS 23.285,    V14.1.0, (2016-12)-   [9] Intelligent Transport Systems (ITS); Framework for Public Mobile    Networks in Cooperative ITS (C-ITS); ETSI TR 102 962 V1.1.1    (2012-02), pp. 37-   [10] Zhang et al., LTE Small Cell Enhancement by Dual Connectivity,    Wireless World Research Forum, White Paper, November 2014.-   [11] Broadcom Corporation, “Mobility for dual connectivity”, T-DOC,    R2-130990, 2013.-   [12] Frédéric Firmin, NAS, 3GPP,    http://www.3gpp.org/technologies/keywords-acronyms/96-nas, Last    Accessed 27 Jan. 2017.-   [13] Developing Solutions, About the S1 Dictionary,    http:/www.developingsolutions.com/S1Dict/Topics/About.htm, Last    Accessed 27 Jan. 2017.-   [14] Intelligent Transport Systems (ITS); Vehicular Communications;    Basic Set of

Applications; Part 2: Specification of Cooperative Awareness BasicService, ETSI TS 102 637-2 V1.2.1, March 2011.

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1. A cellular network supporting a preemptive preparation of a handoverfor a user entity, wherein the cellular network comprises amicroprocessor configured for, or an electronic circuit configured for,or a computer programmed with a program stored in a memory configuredfor request, from the user entity, a transmission of predicted futureroute information; receiving, from the user entity, the predicted futureroute information, the predicted future route information including listof locations along the predicted future route, determining, based on thepredicted future route information, a preliminary set of one or morebase stations of the cellular network, wherein the cardinality of theset of one or more base stations is greater than one; sending a queryfrom a centralized unit of the cellular network to each of thepreliminary set of one or more base stations of the cellular networkregarding an accessibility of the cellular network via the respectivebase station at an expected time at which the user entity enters a cellof the respective base station, and sending an answer from therespective base station to the centralized unit.
 2. (canceled) 3.(canceled)
 4. (canceled)
 5. (canceled)
 6. The cellular network accordingto claim 1, configured for: establishing, for each base station x of aset of one or more base stations of the cellular network, a temporalaccess interval starting at start time t^(x) _(start) and one or moreaccess parameters so that the user entity may access the cellularnetwork via the respective base station during the temporal accessinterval using the one or more access parameters; and sending to theuser entity a schedule indicating the start time t^(x) _(start) and theone or more access parameters for each base station x of the set of oneor more base stations.
 7. The cellular network according to claim 1,configured for establishing, for each base station x of a set of one ormore base stations of the cellular network, a temporal access intervalstarting at start time t^(x) _(start) and ending at a temporal, end andone or more access parameters, so that the user entity may access thecellular network via the respective base station during the temporalaccess interval using the one or more access parameters; and sending tothe user entity a schedule indicating the start time t^(x) _(start) andthe one or more access parameters and as to when the temporal accessinterval ends for each base station x of the set of one or more basestations.
 8. The cellular network according to claim 1, wherein thecellular network is configured to determine the set of one or more basestations of the cellular network based on the predicted future routeinformation such that the set of one or more base stations arepositioned alongside the predicted future route.
 9. (canceled)
 10. Thecellular network according to claim 1, wherein the query comprisesinformation on one or more current identifiers with which the userentity is identified in the cellular network.
 11. The cellular networkaccording to claim 6, configured so that each of the set of one or morebase stations reserves radio access resources defined by the one or moreaccess parameters for the respective base station during the temporalaccess interval for the respective base station.
 12. The cellularnetwork according to claim 6, configured to perform the preemptivepreparation of the handover by further scheduling, for each of the setof one or more base stations of the cellular network, a redirection ofpackets of one or communications running over the cellular network andthe user entity so that the packets are distributed to each of the setof one or more base stations of the cellular network depending on thetemporal access interval for the respective base station.
 13. (canceled)14. The cellular network according to claim 6, wherein the cellularnetwork is configured to establish, at least for one of the set of oneor more base stations, the temporal access interval such that thetemporal access interval comprises a future start.
 15. The cellularnetwork according to claim 6, configured to provide the user entity witha schedule indicating, at least for each of a subset of the set of oneor more base stations, the temporal access interval and the one or moreaccess parameters.
 16. The cellular network according to claim 6,configured to, triggered by an access of the cellular network by theuser entity via one of the set of one or more base stations, to redirecta cellular network internal subpath of each of a set of currentcommunication paths running via the cellular network and the userentity, from a base station via which the user entity is currentlyconnected to the cellular network, to the one of the set of basestations.
 17. The cellular network according to claim 6, configured to,triggered by an access of the cellular network by the user entity viaone of the set of one or more base stations, to further releaseresources at a base station via which the user entity previouslyconnected to the cellular network.
 18. The cellular network according toclaim 1, configured to resume connectivity to the user entity after lossof the connectivity to the user entity via the preemptively preparedhandover.
 19. (canceled)
 20. (canceled)
 21. (canceled)
 22. (canceled)23. (canceled)
 24. A user entity for communication over a cellularnetwork, wherein the user entity comprises a microprocessor configuredfor, or an electronic circuit configured for, or a computer programmedwith a program stored in a memory configured for gaining information ona predicted future route of the user entity; and informing, upon arequest from the cellular network, the cellular network on the predictedfuture route by sending to the cellular network a list of locationsalong the predicted future route; manacling a set of one or morepreemptively prepared handovers by deriving, for each of a set of one ormore base stations of the cellular network, one or more accessparameters, and continuously deciding on, or judging whether, accessingthe cellular network via any of the set of one or more base stationswithin a reach of which the user entity currently is, using the one ormore access parameters derived for the respective base station, whereinthe cardinality of the set of one or more base stations is greater thanone.
 25. (canceled)
 26. The user entity according to claim 24, whereinthe user entity is configured to manage a set of one or morepreemptively prepared handovers.
 27. The user entity according to claim26, configured to receive a schedule scheduling the set of one or morepreemptively prepared handovers from the cellular network.
 28. The userentity according to claim 27, wherein the user entity is configured tocontinuously check, subsequent to the reception of the schedule from thecellular network, whether the schedule becomes inadequate, and informthe cellular network on the inadequateness.
 29. The user entityaccording to claim 26, configured to derive from the schedule, for eachof a set of one or more base stations of the cellular network, atemporal access interval and one or more access parameters.
 30. The userentity according to claim 26, configured to derive from the schedule,for each of a set of one or more base stations of the cellular network,a start time of a temporal access interval and one or more accessparameters.
 31. (canceled)
 32. (canceled)
 33. (canceled)
 34. (canceled)35. The user entity according to claim 26, configured to perform thecontinuous deciding or judgment without acquiring current permissionfrom the cellular network.
 36. The user entity according to claim 26,configured to perform the managing of the set of one or morepreemptively prepared handovers with respect to one or more wirelessconnections to the cellular network of a set of current wirelessconnections to the cellular network.
 37. The user entity according toclaim 26, configured to resume connectivity to the cellular networkafter loss of the connectivity using any of the set of one or morepreemptively prepared handovers despite a temporary loss of connection.38. A base station of a cellular network configured to, wherein the basestation comprises a microprocessor configured for, or an electroniccircuit configured for, or a computer programmed with a program storedin a memory configured for receiving from a user entity predicted futureroute information including a list of locations along the predictedfuture route; determining a preliminary set of one or more target basestations of the cellular network based on the predicted future routeinformation, wherein the cardinality of the preliminary set of one ormore base stations is greater than one; querying each of the preliminaryset of one or more target base stations regarding an accessibility ofthe cellular network via the respective target base station; receiving,from each of the preliminary set of one or more base stations, an answerto the query; sending to the user entity a schedule indicating, for eachof a set of one or more base stations within the preliminary set, atemporal access interval and one or more access parameters indicatingthat the user entity may access the cellular network via the respectivebase station during the temporal access interval using the one or moreaccess parameters, and cutting, upon receipt of an access confirmationfrom any of the set of one or more base stations, a connection to theuser entity.
 39. (canceled)
 40. The base station according to claim 38,configured to determine the preliminary set of one or more base stationsof the cellular network based on the predicted future route such thatthe set of one or more base stations are positioned alongside thepredicted future route.
 41. The base station according to claim 38,configured so that the query comprises information on one or morecurrent identifiers using which the user entity is identified in thecellular network.
 42. (canceled)
 43. The base station according to claim38, configured to query each of the preliminary set of one or more basestations of the cellular network regarding an accessibility of thecellular network via the respective base station at an expected time atwhich the user entity enters the respective cell according to thepredicted future route.
 44. The base station according to claim 38,wherein the cardinality of the set of one or more base stations isgreater than one.
 45. The base station according to claim 38, configuredsuch that, at least for one of the set of one or more base stations, thetemporal access interval comprises a future start.
 46. The base stationaccording to claim 38, configured to allow a resuming of connectivity tothe user entity after loss of the connectivity using the temporal accessinterval and the one or more access parameters for any of the set of oneor more base stations.
 47. The base station according to claim 38,configured to indicate in the schedule a start time t^(x) _(start) ofthe temporal access interval and the one or more access parameters foreach base station x of the set of one or more base stations.
 48. Thebase station according to claim 38, configured to indicate in theschedule a start time t^(x) _(start) of the temporal access interval,the one or more access parameters and as to when the temporal accessinterval ends for each base station x of the set of one or more basestations. 49.-57. (canceled)
 58. A method for operating a cellularnetwork comprising preemptively preparing a handover for a user entity,wherein the method performed on a microprocessor or electronic circuitcomprises requesting, from the user entity, a transmission of predictedfuture route information; receiving, from the user entity, the predictedfuture route information, the predicted future route informationincluding a list of locations along the predicted future route;determining, based on the predicted future route information, apreliminary set of one or more base stations of the cellular network,wherein the cardinality of the set of one or more base stations isgreater than one; sending a query from a centralized unit of thecellular network to each of the preliminary set of one or more basestations of the cellular network regarding an accessibility of thecellular network via the respective base station at an expected time atwhich the user entity enters a cell of the respective base station; andsending an answer from the respective base station to the centralizedunit.
 59. (canceled)
 60. A method for communication from a user entityover a cellular network, comprising gaining information on a predictedfuture route of the user entity and informing, upon the request from thecellular network, the cellular network on the predicted future route bysending to the cellular network a list of locations along the predictedfuture route, managing a set of one or more preemptively preparedhandovers by deriving, for each of a set of one or more base stations ofthe cellular network, one or more access parameters, and continuouslydeciding on, or judging whether, accessing the cellular network via anyof a set of one or more base stations within a reach of which the userentity currently is, using the one or more access parameters derived forthe respective base station, wherein the cardinality of the set of oneor more base stations is greater than one.
 61. The method of claim 60,further comprising managing a set of one or more preemptively preparedhandovers.
 62. A method of operating a base station of a cellularnetwork, comprising requesting, from a user entity, a transmission ofpredicted future route information; receiving, from the user entity, thepredicted future route information, the predicted future routeinformation including a list of locations along the predicted futureroute; determining a preliminary set of one or more target base stationsof the cellular network based on a predicted future route information,wherein the cardinality of the preliminary set of one or more basestations is greater than one; and triggered by the user entity enteringa predetermined area, querying each of the preliminary set of one ormore target base stations regarding an accessibility of the cellularnetwork via the respective target base station receiving, from each ofthe preliminary set of one or more base stations, an answer to thequery; sending to the user entity a schedule indicating, for each of aset of one or more base stations within the preliminary set, a temporalaccess interval and one or more access parameters indicating that theuser entity may access the cellular network via the respective basestation during the temporal access interval using the one or more accessparameters; and cutting, upon receipt of an access confirmation from anyof the set of one or more base stations, a connection to the userentity. 63-66. (canceled)